Motion in a Plane - Result Question 21
23. The angle between $\vec{A}$ and $\vec{B}$ is $\theta$. The value of the triple product $\vec{A} \cdot(\vec{B} \times \vec{A})$ is
[1989]
(a) $A^{2} B$
(c) $A^{2} B \sin \theta$
(b) zero
(d) $A^{2} B \cos \theta$
Show Answer
Answer:
Correct Answer: 23. (b)
Solution:
- (b) Note that $(\vec{B} \times \vec{A}) \perp \vec{A}$. Hence their dot product is zero.
Dot product of any two perpendicular vector is zero
